Question: Subtract.
Explanation: There are many ways to solve this problem. Let's see two ways we can solve it. Place Value We can think in terms of tenths: $\begin{aligned} &\phantom{=}28-13.5\\\\ &=28.0-13.5\\\\ &=280\text{ tenths} - 135\text{ tenths}\\\\ &=145\text{ tenths}\\\\ &=14.5 \end{aligned}$ Place value table Let's line up the numbers by their decimal places. Tens Ones $.$ Tenths $2$ ${8}$ $.$ ${0}$ $1$ $3$ $.$ ${5}$ Now, let's subtract each place value column. Tens Ones $.$ Tenths ${2}$ $\overset{7}{\cancel{{8}}}$ $.$ $\overset{10}{\cancel{{0}}}$ $-$ $1$ ${3}$ $.$ ${5}$ $\underline{~~~~}$ $\underline{~~~~}$ $\underline{~~~~}$ $\underline{~~~~}$ $1$ $4$ $.$ $5$ $14.5 = 28 - 13.5$